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change logger to be limited by file size
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change logger to be limited by file size
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move datatable to yarn
 r789 # static-eval
evaluate statically-analyzable expressions
[![testling badge](https://ci.testling.com/substack/static-eval.png)](https://ci.testling.com/substack/static-eval)
[![build status](https://secure.travis-ci.org/browserify/static-eval.png)](http://travis-ci.org/browserify/static-eval)
# security
static-eval is like `eval`. It is intended for use in build scripts and code transformations, doing some evaluation at build time—it is **NOT** suitable for handling arbitrary untrusted user input. Malicious user input _can_ execute arbitrary code.
# example
``` js
var evaluate = require('static-eval');
var parse = require('esprima').parse;
var src = process.argv[2];
var ast = parse(src).body[0].expression;
console.log(evaluate(ast));
```
If you stick to simple expressions, the result is statically analyzable:
```
$ node '7*8+9'
65
$ node eval.js '[1,2,3+4*5-(5*11)]'
[ 1, 2, -32 ]
```
but if you use statements, undeclared identifiers, or syntax, the result is no
longer statically analyzable and `evaluate()` returns `undefined`:
```
$ node eval.js '1+2+3*n'
undefined
$ node eval.js 'x=5; x*2'
undefined
$ node eval.js '5-4*3'
-7
```
You can also declare variables and functions to use in the static evaluation:
``` js
var evaluate = require('static-eval');
var parse = require('esprima').parse;
var src = '[1,2,3+4*10+n,foo(3+5),obj[""+"x"].y]';
var ast = parse(src).body[0].expression;
console.log(evaluate(ast, {
n: 6,
foo: function (x) { return x * 100 },
obj: { x: { y: 555 } }
}));
```
# methods
``` js
var evaluate = require('static-eval');
```
## evaluate(ast, vars={})
Evaluate the [esprima](https://npmjs.org/package/esprima)-parsed abstract syntax
tree object `ast` with an optional collection of variables `vars` to use in the
static expression resolution.
If the expression contained in `ast` can't be statically resolved, `evaluate()`
returns undefined.
# install
With [npm](https://npmjs.org) do:
```
npm install static-eval
```
# license
MIT